Method of forming copper interconnections in semiconductor devices

ABSTRACT

A method of forming a copper interconnection including at least one of: Forming an interlayer dielectric layer over a silicon substrate. Forming a plurality of via holes and trench patterns in an interlayer dielectric layer; forming a photoresist pattern over an interlayer dielectric layer between a plurality of via hole and trench patterns. Performing an electroplating process on a silicon substrate so that copper may be filled in a plurality of via holes and trench patterns. Planarizing a copper layer so that a photoresist pattern is removed.

The present application claims priority under 35 U.S.C. 119 and 35 U.S.C. 365 to Korean Patent Application No. 10-2005-0133479 (filed on Dec. 29, 2005), which is hereby incorporated by reference in its entirety.

BACKGROUND

Some semiconductor device may have relatively fast response speeds. Semiconductor device may use low dielectric materials (i.e. low-k materials) for a relatively low dielectric constant in materials, which may minimize RC delays. Semiconductor devices may use copper (Cu) with relatively low resistivity in metal interconnections, which may reduce RC delays.

Since wet etching copper may be difficult, a damascene process may be used to form copper interconnections. In a damascene process, via holes and/or trenches may be formed by selectively etching an interlayer dielectric layer (e.g. having a low dielectric layer) to form via holes and/or trenches. In a damascene process via holes and/or trenches may be filled with copper (e.g. through an electroplating process) to form metal interconnections.

Electro-chemical plating (ECP) may be used as an electroplating process to form a copper interconnection. ECP equipment may precipitate a wafer in a water tank including an electrolyte. ECP equipment may apply a voltage to a copper electrode in the water tank and a semiconductor wafer to electroplate copper on the wafer. A copper layer electroplated on a wafer may be formed on the entire surface of the wafer covered with an electrolytic solution.

As illustrated in FIG. 1 a, copper may be plated in patterns 5 (e.g. via holes, trenches and similar structures) and over other surfaces of a wafer. During electroplating, current may be concentrated in area A (e.g. a second of a dielectric layer having an elaborate pattern). Concentration of current may result in a hump phenomenon with a relatively large amount of copper being formed in area A. A smaller amount of copper may be deposited in area B, due to current distribution during electroplating. Copper may be electroplated in area B relatively slow, resulting in a relatively broad pattern width.

Copper may be formed to have a thickness of about 3000 Å or more in area A during an approximate 10 seconds electroplating duration. Since copper may be plated higher in area A than area B, a step difference in a copper layer may be formed. A step difference in a copper layer may cause complications during planarization of the copper layer. If a step difference is too large, a copper layer in area A may remain higher than a desired height and/or a copper layer in area B may be shorter than a desired height, as illustrated in FIG. 1 b.

A step difference of a copper layer may be reduced by excessively depositing a copper layer, which may be accomplished by excessive electroplating. For example, copper may be excessively electroplated to a height of approximately 10000 Å. Excessively electroplating may increase manufacturing costs and/or increase the time of a planarization process.

SUMMARY

Embodiments relate to a method of forming a copper interconnection. In embodiments, a surface of a wafer may be uniformly planarized after electroplating in a damascene process.

Embodiments relate to a method of forming a copper interconnection including at least one of: forming an interlayer dielectric layer over a silicon substrate; forming a plurality of via holes and trench patterns in an interlayer dielectric layer; forming a photoresist pattern over an interlayer dielectric layer between a plurality of via hole and trench patterns; performing an electroplating process on a silicon substrate so that copper may be filled in a plurality of via holes and trench patterns; and planarizing a copper layer so that a photoresist pattern is removed.

In embodiments, the thickness of a copper layer formed through an electroplating process is less than approximately 5000 Å. In embodiments, a plurality of via holes and trench patterns may be formed in concentration and non-concentration areas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a and 1 b are sectional views illustrating the formation of a copper interconnection.

Example FIGS. 2 a to 2 d are sectional views illustrating methods of forming a copper interconnection, according to embodiments.

DETAILED DESCRIPTION

Example FIGS. 2 a to 2 d are sectional views illustrating methods of forming a copper interconnection, according to embodiments. As illustrated in FIG. 2 a, dielectric layer 2 may be formed over a semiconductor substrate, in accordance with embodiments. An oxide layer 4 may be formed over dielectric layer 2. A photo-etching process may be performed on interlayer dielectric layer 2 and/or oxide layer 4 to form patterns 15. Patterns 15 may include at least one via hole and/or at least one trench and/or a similar structure. Copper may fill patterns 15 to form interconnections.

After forming patterns 15, barrier layer 8 may be formed. Barrier 8 may facilitate the deposition of copper during an electroplating process, in accordance with embodiments. In embodiments, barrier 8 may prevent the diffusion of copper. In embodiments, barrier 8 may include TaN.

As illustrated in FIG. 2 b, a photoresist pattern 6 is formed between the patterns 15, in accordance with embodiments. Photoresist material 6 may be formed over unetched areas of interlayer dielectric layer 2 and/or unetched areas of oxide layer 4. Photoresist material 6 may be formed between patterns 15 (e.g. via holes and/or trenches).

As illustrated in FIG. 2 c, an electroplating process may be performed over interlayer dielectric layer 2, oxide layer 4, barrier 8, and/or photoresist material 6, in accordance with embodiments. In embodiments, electroplating may be performed using electrochemical plating (ECP) equipment. From electroplating, copper layer 21 may be formed.

ECP equipment may include a copper electrode in a water tank, containing an electrolytic solution. A wafer may be electroplated by being precipitated with an electrolytic solution in a water tank. A voltage may be applied to a copper electrode and a wafer such that copper is plated on the wafer through electrolysis. In embodiments, copper may be deposited with a thickness of less than approximately 7000 Å. In embodiments, copper may be deposited with a thickness of less than approximately 5000 Å.

In embodiments, a photoresist pattern having low solidity may be formed on areas in which patterns are not formed before electroplating copper. A photoresist pattern may allow for effective planarization of copper, without excessive electroplating of copper, in accordance with embodiments.

In embodiments, copper layer 21 is formed relatively high in area A′. Area A′ may include finely formed patterns 15. Because photoresist pattern 6 is formed at a lower portion of copper layer 21, planarization may be performed with relative ease, such that the copper layer 21 is prevented from being over etched or under etched, in accordance with embodiments. In embodiments, since photoresist pattern 6 is not formed in area B′ (in which copper layer 21 may be formed relatively low), area B′ may be planarized to a level substantially the same as area A′. Pattern area A′ may be a concentration area. Pattern area B′ may be a non-concentration area. In embodiments, concentration areas and non-concentration areas may be planarized to substantially the same level.

In embodiments, the planarity of a surface of a wafer may be adjusted in a chemical mechanical polishing process. In embodiments, a surface may be uniformly planarized, as illustrated in example FIG. 2 d. In embodiments, when a copper interconnection is formed, excessive deposition of copper layer may not be necessary. In embodiments, by avoiding excessive copper deposition, manufacturing costs may be reduced. In embodiments, by avoiding excessive copper deposition, the time required for a planarization process may be reduce, which may increase the efficiency of a manufacturing process.

It will be apparent to those skilled in the art that various modifications and variations can be made to embodiments. Thus, it is intended that embodiments cover modifications and variations thereof within the scope of the appended claims. 

1. A method comprising: forming a dielectric layer over a semiconductor substrate; forming at least one of a via hole and a trench pattern in the dielectric layer; forming a photoresist pattern over the dielectric layer in areas wherein said at least one of a via hole and a trench pattern are not formed; and electroplating metal over said photoresist pattern.
 2. The method of claim 1, comprising planarizing electroplated metal.
 3. The method of claim 2, wherein said planarizing comprises removing the photoresist pattern.
 4. The method of claim 1, wherein the method forms a copper interconnection.
 5. The method of claim 1, wherein the dielectric layer is an interlayer dielectric layer.
 6. The method of claim 1, wherein said electroplating metal is electroplating copper.
 7. The method of claim 1, wherein said electroplating metal comprises filling said at least one of a via hole and a trench pattern with metal.
 8. The method of claim 1, wherein the dielectric layer comprises a low-k dielectric material.
 9. The method of claim 1, wherein said electroplating metal comprises electroplating metal to have a thickness less than approximately 7000 Å.
 10. The method of claim 9, wherein said electroplating metal comprises electroplating metal to have a thickness less than approximately 5000 Å.
 11. The method of claim 1, wherein said at least one of a via hole and a trench pattern include concentration and non-concentration areas.
 12. An apparatus comprising: a dielectric layer formed over a semiconductor substrate; at least one of a via hole and a trench pattern formed in the dielectric layer; and metal electroplated over said photoresist pattern, wherein the metal is electroplated by forming a photoresist pattern formed over the dielectric layer in areas wherein said at least one of a via hole and a trench pattern are not formed.
 13. The apparatus of claim 12, wherein the metal is planarized.
 14. The apparatus of claim 13, wherein photoresist pattern is removed when the metal is planarized.
 15. The apparatus of claim 12, wherein the dielectric layer is an interlayer dielectric layer.
 16. The apparatus of claim 12, wherein said metal is copper.
 17. The apparatus of claim 12, wherein the dielectric layer comprises a low-k dielectric material.
 18. The apparatus of claim 12, wherein the metal is electroplated to have a thickness less than approximately 7000 Å.
 19. The apparatus of claim 18, wherein the metal is electroplated to have a thickness less than approximately 5000 Å.
 20. The apparatus of claim 12, wherein said at least one of a via hole and a trench pattern include concentration and non-concentration areas. 